' 


Circular  No.  9) 


I  UHJH 


I  oited  States  Department  of  Agricu 

BUREAU  OP  ENTOMOLOGY, 

L.  O.  HOWAK1)    KntomologUt  »nd  Chief..!  Bw 


THE  BAGWORH. 

(TTtyridopUryx  tphemei  11. iu 

By  l     0.   I  fott  uuj  and  I     II    Cbittkndi 

m  i:  \\     \rri\i;\Mi      \m-    NATUB1     "i      kTTACK. 

Shade  tret-,  -hrui>-.  and  hedges,  and  in  particular  evergreens,  are 
much  Bubject  to  injury  by  a  medium  sized  caterpillar  which  ha-  a 
curious  habit  <>t'  crawling  about  <>n  the  infested  trees  in  a  bag-like  case, 
whence  its  common  name  of  bagwormor  basket  worm. 
In  the  shelter  <>('  these  cases  the  insects  undergo  all 
their  transformations,  after  which  the  bags  remain 
attached  to  the  plant-  for  some  time  and  are  conspic- 
uous objects  on  leafless  trees  and  shrubs  in  late  autumn 
mill  in  winter.  Like  the  tussock  moth  and  the  tall 
webworm*  tin-  species  i-  preeminently  a  pest  on  the 
Btreets  and  in  park-  and  private  grounds  <>!'  cities  and 
towns  and  is  even  more  subject  to  fluctuation  in  num- 
bers. It  i-.  however,  more  limited  in  distribution 
and  nut  found  a-  a  rule  north  of  southern  New  York 
and  the  central  portions  of  Pennsylvania  and  Ohio. 
South  of  these  points  it  i-  in  certain  years  very  trou- 
blesome and  tin-  subject  of  much  complaint  Such  a 
year  was  1907,  when  the  bagworm  attracted  greater 
attention  than  any  other  tree  defoliator.  Numerous 
complaints  were  received  of  injuries  in  the  region 
mentioned,  and  especially  from  the  State-  of  New 
Jersey,    Pennsylvania,    Maryland.   Virginia,    West   Virginia,   Ohio, 

Indiana,   and    Illinoi-.      d"he   natural  enemies  of  thi-   insect   (see   p.   »'•> 

were  comparatively  scarce,  and  there  i-  a  strong  possibility  of  a  recur- 
rence of  injuries  in  the  year-  to  come. 

The  general  appearance  of  the  bagworm  i-  shown  in  figure  I.  which 
illustrates  the  caterpillar  when  nearly  full  grown,  in  it-  characteristic 
bag.  When  removed  from  it-  bag  it  look-  a-  shown  in  figure  8,  •  '. 
which  represents  the  larva H  maturity.     A4~tlu-  period  in  it-  develop- 


I    •.     I   —  Rac«  ..mi 
(  Thyriilnplrryl 

Natural  - 

tor  i: 


lerocnmp  18.  A  A. 

-       -Cir.  97—08 1 


ment  it  may  attain  a  length  of  about  three-fourths  of  an  inch.  The 
body  is  soft  in  texture  and  dull  brownish  or  blackish,  while  the  head 
and  thoracic  Begments  arc  horny  and  whitish,  mottled  with  dark 
brown. 

ORIGINAL   HOME   AM)   PRESENT   DISTRIBUTION. 

The  bagworm  is  unquestionably  native  to  North  America.  It 
abounds  in  the  Southern  States,  and  its  proper  home— that  is  to  say, 
the  part  of  the  country  where  it  reaches  its  maximum — is  in  the  Lower 
Austral  life  zone.  It  extends  thl'OU'gh  a  considerable  portion  of  the 
Upper  Austral  zone,  hut  there  are  indications  that  it  has  gradual!}' 
spread  into  this  territory  from  more  southern  regions."  The  shade 
trees  of  Baltimore.  Washington,  St.  Louis,  and  other  more  southern 
cities  are  frequently  defoliated  by  this  insect.     Northward  it  occurs 


Kn..  -. — Bagworm  (  Thyridopteryxephemerstformia} :  a,  Fall-grown  larva:  /<.  head  of  same:  c,  male  pupa; 
•  /,  female  pupa;  e,  adult  female;  /,  adult  male.    All  enlarged  (from  Howard  . 

through  New  Jersey  and  at  many  points  in  Pennsylvania,  including 
the  cities  of  Harrisburg,  Elliottsburg,  Allentown,  and  Swarthmore. 

Farther  west  it  has  been  found  at  Columbus,  Marietta,  South  Salem, 
and  other  localities  in  Ohio,  at  several  points  in  West  Virginia,  at 
Brooklyn,  Ind.,in  Pecatonica,  ThompsonviUe,  and  Allendale.  111.,  and 
so  on  west  to  Oklahoma.  Everywhere  south  of  these  localities,  except 
in  the  immediate  Gulf  region,  it  abounds.  In  the  East  it  is  commonly 
found  in  New  York  City  and  Brooklyn,  and  at  several  points  on  Long 
Island.  In  the  Hudson  River  Valley  region  it  has  been  recorded  by 
Felt  at  Yonkers  and  Mount  Vernon,  and  has  been  collected  at  New 

"  In  the  main  the  bagworm  is  one  of  those  characteristic  forms  like  the  wheel-bug 
[Arilus  cristatus  Jj.) ,  the  Carolina  mantis  [Stagmomantis  Carolina  L.),  and  the  la' 
<li'_rL.'cr  wasp  (Sphecivs  speciosus  Drn.i,  true  southern  forms  which  are  gradually 
extending  their  northward  range  by  following  the  Beacoast  or  valleys,  or.  if  carried 
accidentally  mirth  ward  upon  railroad  trains,  establishing  themselves  at  points  beyond 
their  former  habitat. 


--•urn!.' 


Haven.  Conn.,  but  it  is  not  known  to  be  injurious  in  these  localities. 
Tt  has  been  sent  to  the  Bureau  of  Entomology  from  Springfield,  Ma—.. 

but  probably  does  not  breed  there. 

FOOD   PLANTS. 

The  bagworm,  although  a  very  general  feeder,  displays  a  particular 
fondness  for  evergreens  of  all  kinds  and  especially  for  arborvitae, 
hence  it  seems  probable  that  one  or  the  other  of  these  was  its  original 

or  normal  food  plant  (fig.  3).  The  species  becomes  exceedingly  abun- 
dant every  few  years,  and  at  such  times  it  may  be  found  on  shade, 
orchard,  and  forest  trees  of  nearly  all  kinds.  It  is  fond  of  the  maples, 
particularly  the  cut-leaved  and  silver  maples,  and  the  related  box 
elder;  also  of  the  poplars  and  mulberry,  less  so  of  the  elms,  and 
apparently  still  less  so  of  the  oaks.  It  feeds  more  or  less  freely,  how- 
ever, on  most  other  trees  and  shrubs,  and  even  on  many  low-growing 
semi-woody  plants,  such  as  elder,  mallows  (Hibiscus),  and  ragweed 
(Ambrosia  trip'iln).  Thus,  in  the  absence  of  its  choice  food  plants,  it 
is  able  to  subsist  on  the  foliage  of  almost  any  of  the  plants  of  the 
character  enumerated  and  which  ma}'  be  available,  but  it  does  not 
seem  to  live  on  grasses  and  herbaceous  plants  generalhT. 

HABITS   AXD   LIFE    HISTORY. 

The  bagworm  overwinters  in  the  c<>g  stage  within  the  old  female 
bags,  and  for  this  reason  hand-picking  in  winter  time  is  an  efficacious 
remedy.  In  the  late  spring  the  young  hatch  from  the  eggs,  crawl  out 
upon  the  twigs,  make  their  way  to  the  nearest  leaf,  and  immediately 
begin  to  feed  and  to  construct  cases  or  bags  for  themselves.  They 
spin  a  large  amount  of  silk  and  attach  to  it,  for  additional  strength 
and  protection,  bits  of  leaf  or  of  twig,  evidently  attempting  to  disguise 
the  nature  of  the  case  as  well  as  to  strengthen  it.  The  larva  i- 
remarkably  soft-bodied,  except  for  its  head  and  strong  thoracic  plates, 
and  it  is  necessary  that  the  soft  abdomen  should  have  some  protection. 
The  construction  of  the  bag  of  an  allied  species  was  carefully  studied 
by  H.  G.  Hubbard,  and  it  is  a  very  interesting  performance. 

The  young  larva  (tig.  4,  <i)  cuts  off  with  its  jaws  a  small  fragment  of 
leaf  which  it  places  between  its  front  legs,  gradually  forming  a  pile 
fastened  loosely  with  silk.  When  the  pile  becomes  a  transverse  tangle 
about  as  long  as  the  body  it  i-  fastened  at  each  end  loosely  to  the  surface 
upon  which  it  rests;  then  the  caterpillar,  after  placing  itself  at  light 
angles,  dives  under  the  mass,  turning  a  complete  somersault,  so  that  it 
lies  on  its  back,  bound  down  by  the  fillet.  It  then  twists  around  and 
stands  upon  its  feet,  having  its  neck  under  a  sort  of  yoke  (fig.  4,  h). 
It  makes  the  }*oke  into  a  complete  collar,  adding  bits  to  each  end  until 

[Cir.  97] 


5 


the  circle  is  complete.    Then  row   after  row   of  fragments  is  added 

until  the  case  becomes  a  hollow  cylinder  (fig.  l.  •  i.     One  end  is  then 

closed  up  and  the  inside  lined  with  a  toagfa  coating  of  silk,  thi 

being  then  extended  upright  and  fastened  at  one  end.     Whenit  is  fully 

completed  the  larva  crawls  away,  with  the  case  carried  upright  like 

a  cap  <»n  the  upturned  end  of  it-  body,     in  the  illustration  d  shows  a 

oompleted  bag  made  bj   the  young  larva,  tightly  appressed  to  the  flat 

surface,  the  larva  being  concealed  within.     Such  bags  maj  frequently 

be  found  on  [ea\  es,  and 

are  quite  puzzling  to  the 

uninitiate d  until  the 

Ian ;i  pokes  <>ut  it-  head 

and    slow  ly    walk-   off. 

A-  tin-  caterpillar  grows 

tin'    case    i-    constantly 

enlarged,  bits  of  twigs 

and    any    ot  her   small 

objects    being   used    to 

ornament     the    outside, 

and    these    objects    will 

vary    w  itli    the   kind    of 

tree    14)011    w  li  i  c  li    the 

caterpillar  i-  feed  i  n  g. 

While  the  Ian  a  is  small 

it  carries  it-  case  erect, 

t>ut  \\  hen  it  i-  larger  the 

case  hangs  dow  n  ( fig.  1 1. 

The  larval  skin   is  cast 

four   times,   and   during 

the  molting  the  mouth  of 

the  bag  is  kept   closed 

w  ith    silk.       There    is  a 

small    opening    in    the 

extremity    of   the    hat: 

through     which     excre- 
ment and  cast  skins  are  pushed.    The  male  bags  are  smaller  than  those 

of  the  female-,  reaching  a  length  of  about  an  inch,  while  those  of  the 
females  are  much  larger.  Toward  the  end  of  August,  about  Wash- 
ington, I>.  ('..  the  larva  complete-  it-  growth,  attache-  it-  bag  firmly 
by  a  silken  band  to  a  twig,  strengthens  it  inside  with  an  additional 
layer  >>i  -ilk.  and  within  this  retreat,  which  now  becomes  its  COOOOn, 
transforms  to  pupa  with  its  head  downward.  The  pupal  period  lasts 
about  three  week-,  and  then  the  imago  emerges.  The  male  chrysalis 
work-  it-  way  out  of  the  lower  opening,  and  the  winged  moth  issues 
-Cir.  '.<7-(is 2 


Pic   1     a    Newly  hatched  bagworui  before  makli 

ast  beginnii  •  nearly  com- 

plel  larva 

hi  1  it  lir-t  molt    Highly  1 


through  the  cracking  skin,  leaving  the  chrysalis  hanging  from  the  bag, 
as  shown  at  c,  figure  ">.  The  chrysalis  of  the  female  docs  not  push  its 
way  at  all  out  of  the  bag,  but  the  skin  cracks  and  the  female  gradually 
works  her  way  partly  out,  her  head  reaching  the  lower  end  of  the  bag, 
(lig.  5,  d).  The  males  fly  about,  seeking  the  hags  of  the  females,  and 
when  one  is  found  in  which  the  head  of  the  female  is  near  the  end. 
showing  that  she  has  emerged  from  her  chrysalis  >kin.  the  male  pushes 
his  enormously  protrusive  and, in  fact,  telescopic  genital  apparatus  up 
into  the  bag  to  the  anal  end  of  the  female  and  fertilizes  her.  The 
female  then  works  her  way  back  into  the  chrysalis  skin, gradually  filling 
it  with  eggs  until  more  than  half  of  it  is  filled,  scattering  in  among  the 
eggs  some  of  the  sparse  hairs  from  her  body.     Having  done  this  she 

forces  her  shriveled 
body  out  of  the  open- 
ing, falls  to  the  ground, 
and  dies.  The  eggs  re- 
main in  this  way  until 
the  following  spring, 
when  they  hatch,  as 
previously  described. 

There  is  thus  only  one 
generation  annually. 

Note. — There  is  a  possi- 
bility that  the  bags  of  this 
extremely  common  insert 
might  be  made  commer- 
cially useful.  Itssilk,  from 
a  practical  standpoint,  has 
always  been  ignored,  but  it 
is  firmer  and  stronger  and 
more  easily  spun  as  carded 
silk  than  that  of  must  other 
native  silk  cocoons. 


Fig.  6.— Bagworm  at  (a,  h.  c)  successive  stages  of  growth, 
bag;  •/.  female  bag.    Natural  size  i  from  Howard  I. 


Male 


NATURAL    ENEMIES. 

Although  apparently  well  protected  from  the  attacks  of  birds  b}' 
its  tough  case,  the  bagworm  is  somewhat  extensively  parasitized  by 
several  forms  of  ichneumon  and  chalcis  Hies,  most  of  them  species 
which  affect  also  similar  tree-feeding  caterpillars.  Prominent  among 
these  is  the  common  Pimpla  inquisitor  Say  (fig.  6),  which,  however. 
more  commonly  parasitizes  the  tussock  moth  and  tent  caterpillars. 
The  related  P.  conquisitor  Say  is  also  a  parasite  of  the  bagworm  and 
a  third  species  of  ichneumon,  Allocota  ( II<  mitt  les)  thyridopU  rigis  Riley 
(tig.  7),  is  usually  the  most  abundant  of  all.  Four  or  live  individuals 
of  this  species  comnionlj'  infest  a  single  bagworm,  spinning  for  them- 
selves white  silken  cocoons  within  the  bag. 


fCir.  97 


"  Malacosoma  spp. 


The  species  last  mentioned  was  for  manj  years  credited  with  being 
a  primary  parasite  of  the  bagworm,  although  recenl  observations 
would   indicate  that   it   is  a   secondary  parasite  when  infesting  other 


Kr.  •  male,  from 


Pro,  l.—AUc  M  ii  henlaiged 


caterpillars.     This  mighl  be  explained   by  the  hypothesis  that   this 
parasite  oviposits  onlj  in  cocoons  or  cases  of  firm  texture,  and  there 
fore  can  not  be  the  primary  parasite  of  an  insect  w  bicb  is  not  provided 
with  a  case  of  t liat  character. 


<^K 


Certain  chalcis  flies  also  breed  in 
the  bags  of  tin-  insect.  These  include 
Sjnlochalcls  maria  Riley  Mi;.'.  B), 
Chalets  ovata  Saj  (fig.  9),  and  the 
common  little  Dibrachya  boucheanus 
Rate.  (fig.  10).  Tin-  last  i- a  hyperparasite,  in  the  case  of  the  i>avr- 
worm  probably  secondary,  ami   in  the  case  <>t'  other  cater] 


rpillar 


•    8 

tertiary    parasite.      Habrocytits    thyridopterigi*  Ashm.    (fig.    11)   is 
assumed  to  be  a  tertiary  parasite  on  Allocdta  thyridopterigis  Riley, 

when  the  latter  is  a  secondary  parasite  of  the  tussock  moth,  but  may 
be  secondary  when  breeding  in  the  cases  of  the  bagworm. 

REMEDIES. 


Fig.  10. — Dibrachys  boucheanus:  Adult  female  and  antenna  of  male. 
Much  enlarged  (from  Howard). 


When  the  bagworm  occurs  upon  deciduous  trees  it  can  be  controlled 
by  hand-picking  the  bags  in  the  winter,  but  when  it  affects  evergreen 

trees  it  is  practi- 
cally impossible  to 
apply  this  remedy 
with  profit  unless 
the  plants  arc  badly 
defoliated.  There- 
fore for  the  treat- 
ment of  evergreens 
spraying  is  a  neces- 
sity. 

The  methods  of 
controlling  shade- 
tree  pests  in  cities 
and  towns,  as  out- 
lined in  Farmers' 
Bulletin  No.  99, a  on  pages  25-29,  are  in  part  applicable  to  this  species. 
This  bulletin  should  be  read  by  persons  who  have  experienced  trouble 
from  the  depredations  of  the  bagworm. 

Collecting    the    bags. —  -?• 

One  of  the  most  important 
remedies  consists  in  gath- 
ering the  bags  with  the 
contained  insect  by  hand 
and  either  burning  them 
or  preserving  them  to  lib- 
erate the  useful  parasites 
which  have  been  previ- 
ously mentioned.  This 
work  may  be  facilitated 
by  the  use  of  a  12-foot 
pole    pruner    or    similar 

appliance,  and  can  be  intrusted  to  those  ordinarily  unemployed,  such 
a-  children  and  aged  persons.  Where  the  trees  are  very  tajl  it  will 
be  necessary  to  use  a  long  ladder.  For  best  results  the  cooperation  of 
neighbors  who  are  troubled  with  the  same  pest  should  be  secured. 

«  This  publication  nuty  be  had  gratis  on  application  to  the  Department  of  Agriculture. 
[Cir.  97] 


Fig. 11. 


-Habrocytus  thyridopterigis. 

How  ard  i. 


Greatly  enlarged  (from 


9 

Ycr\  considerable  immunitj  from  future  injury  will  result  bj  care  In 
the  employment  of  this  method.  It  is  particularly  useful  where  on Ij 
a  few  trees  arc  infested.  The  bags  are  Mich  conspicuous  objects  on 
defoliated  or  bare  trees  in  w  inter  thai  it  i-  not  at  all  difficult  to  detect 
them,  l>ni  in  cases  where  comparatively  fe^  insects  are  presenl  on 
evergreen  trees  1 1  •« ■  \  are  not  so  easily  seen. 

Encouraging  ttu  parasite*.  When  many  trees  are  infested  it  is 
advisable  i<>  keep  the  hand  picked  bags  for  a  considerable  time  in 
receptacles,  such  as  barrels  covered  with  netting,  preferably  of  wire, 
bo  that  the  numerous  beneficial  parasites  of  tin-  pest  will  be  able  to 
issue  in  the  spring  and  assist  In  the  control  of  the  bagworm  the  fol 
lowing  rear.  One  or  two  holes  bored  in  the  bottom  of  the  barrel  or 
i»o\  will  prevent  water  from  accumulating  and  drowning  the  insects. 
Where  the  bags  can  be  placed  in  piles  in  an  open  -pace  or  inclosure 
distant  from  trees  and  free  from  disturbance,  the  young  insects,  having 
very  limited  powers  of  locomotion,  will  soon  perish  of  starvation,  as 
they  will  not  be  able  t<>  reach  the  trees  or  shrubs  after  they  batch. 

Spratffng  with  arsenicals.  (  )m  evergreen,  where  the  bags  are  more 
or  less  difficult  to  find,  band-picking  can  not  be  advised.  A  striking 
instance  <  >  t"  the  futility  of  this  method  under  such  circumstances  was 
given  by  Prof.  ('.  V.  Rilej  in  hi-  testimony  at  a  conference  <>n  the 
gipsy  moth  in  1891.  He  said  that  he  once  trie.  I  to  protect  a  cedar  tree 
not  more  than  »;  feet  high,  upon  his  own  grounds  at  Washington,  i>\ 
hand-picking.  lie  worked  tin-  two  consecutive  months  picking  "H 
small  bags  from  that  tree,  the  progeny  of  not  more  than  two  female-. 
Almost  daily  he  went  to  the  tree  and  found  fresh  specimens  which  he 
had  overlooked  the  day  before.  For  evergreen  tree-,  therefore,  an 
arsenical  spray  is  the  best  remedy,  [n  connection  with  the  Btory  of 
hi-  experience  just  related,  Professor  Riley  stated  that  he  had  abso 
lutely  -topped  injury  by  the  bagworm  on  large  tree-  in  the  Smith 
SOnian   grounds    by    -pray  inc.   and    in    the    summer   of    L895    we    had    a 

similar  experience  on  the  grounds  of  the  Agricultural  Department  at 
Washington.  Tree-  sprayed  with  Paris  green  at  the  rate  of  l  pound 
to  150  gallons  of  water  were  completely  rid  of  larva?  of  the  bagworms. 
It  i-  easier  to  reach  the  bagworms  on  evergreen  than  on  large-leaved 

deciduous  -hade  tree-,  -uch  a-  maple  and  elm.  but  if  carefully  carried 

out  spraying  will  result  in  the  destruction  of  the  bagworms,  so  that 

the  collection  of  the  bags  in  winter  will  riot  he  necessary.  Arsenate 
of  lead  at  the  rate  ^i  l  pound  of  the  prepared  paste  f"iin  t.>  from  !'•'> 
to  50  gallons  of  water  will  lie  found  even  more  useful  than  the  Paris 
green,  as  it-  greater  adhesiveness  renders  it  less  likely  to  he  washed 
off  by  rains,  which  in  some  seasons  frequently  occur  almost  daily  at 
the  time  when  the  larv;e  are  beginning  to  work. 
fCir.  97] 


10 

The  best  time  to  apply  the  arsenical  is  when  the  egg*  hatch,  or 
shortly  afterwards,  and  the  best  methods  of  spraying  shade  trees  are 
disclosed  in  Farmers'  Bulletin  No.  !'!». 

Approved: 

James  Wilson, 

Secrt  tary  of  .  Igricultun . 

Washington,  D.  ('..  December®,  1UQ7. 

[Cir.  97] 

O 


UNIVERSITY  OF  FLORIDA 


3  1262  09216  5306 


